An electronic apparatus (e.g., a Personal Computer (PC), a portable terminal, etc.) can include an interface for transmitting/receiving data to/from an external electronic apparatus. Representatively, an electronic apparatus may include a Universal Serial Bus (USB) terminal, and may transmit/receive data to/from the external electronic apparatus through the USB terminal, or may transmit/receive data to/from the external electronic apparatus through a wireless communication module (e.g., Wi-Fi, Bluetooth, etc.).
The USB provides PC users with an enhanced and easy-to-use interface that connects an incredibly diverse range of peripherals to their computers. Among the many advantages of the USB is a reduction in the proliferation of cables which may affect even the smallest computer installations.
Also, the USB provides simple connectivity to users. The USB can eliminate the need to have different connectors for printers, keyboards, mice, and other peripherals, and can support a wide variety of data types, from slow mouse inputs to digitized audio and compressed video.
Today's USB devices that can all communicate with a host computer system over USB include USB printers, scanners, digital cameras, storage devices, card readers, and the like. USB-based systems may require that a USB host controller be present in the host system, and that an operating system (OS) of the host system support USB and USB mass storage class devices. USB devices may communicate over the USB bus at low speed, full speed, high speed, or super speed. A USB electronic device may support only USB 2.0 or may support both USB 2.0 and USB 3.0, according to the required USB data transmission speed. In the USB 2.0, a connection between the USB device and the host includes a power line, a ground line, and data communication lines D+ and D−. When a USB device is connected to the host, the USB device first pulls a D+ line high (a D− line when the device is a low-speed device) by using a pull-up resistor on the D+ line. The host may respond by resetting the USB device. When the USB device is a high-speed USB device, the USB device may chirp by driving the D− line high during the reset. The host may respond to the chirp by alternately driving the D+ and D− lines high. The USB device may then bypass the pull-up resistor, and may continuously perform communication at high speed.
When such an USB is connected to the electronic apparatus and data is transmitted/received between the USB and the electronic apparatus, the electronic apparatus may use an equalizer to improve the quality of transmitted data (or a transmitted signal). The equalizer may be inserted into a transmission circuit or an amplification circuit. The equalizer compensates for signal loss of a high-frequency signal generated from a channel. Examples of equalizers may include an active equalizer or a passive equalizer. An active equalizer may also be known as a continuous time linear equalizer. A passive equalizer may use a resistor and an inductor. Since the passive equalizer would have passive components, the passive equalizer would have low manufacturing costs, and can be used for a high-speed interface, such as Peripheral Component Interconnect express (PCIe), USB 3.0, and the like.